Poly(oxybutylene)poly(oxyethylene)diamine compound and ORI-inhibited motor fuel composition

ABSTRACT

A novel oil-soluble polyether diamine compound, a concentrate comprising the compound dissolved in a hydrocarbon solvent, and a haze-free, deposit-resistant and ORI-inhibited motor fuel composition comprising the compound is described. Motor fuel compositions comprising the novel polyether diamine compound of the instant invention are haze-free and improve ORI control and carbonaceous deposit inhibition in motor fuels. Motor fuel compositions of the instant invention may optionally comprise a polyolefin polymer/copolymer component having a molecular weight range of about 500-3500.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a novel oil-soluble polyester diaminecompound, to a concentrate comprising the polyether diamine dissolved ina hydrocarbon solvent, and to a haze-free, ORI-inhibited anddeposit-resistant motor fuel composition comprising the polyetherdiamine. More particularly, this invention relates to: (i) a novelpolyether diamine compound block copolymers; (ii) a concentratecomprising the novel polyether diamine dissolved in a hydrocarbonsolvent; and (iii) a motor fuel composition comprising the novelpolyether diamine. Motor fuel compositions comprising the polyoxalkylenediamine of the instant invention are haze-free, ORI-inhibited and have areduced tendency to form depostis. Motor fuel compositions of theinstant invention may additionally comprise a polymer/copolymercomponent.

Combustion of a hydrocarbonaceous motor fuel in an internal combustionengine results in the formation and accumulation of deposits on variousparts of the combustion chamber as well as on the fuel intake andexhaust systems of the engine. The presence of deposits in thecombustion chamber seriously reduces the operating efficiency of theengine. First, deposit accumulation within the combustion chamberinhibits heat transfer between the chamber and the engine coolingsystem. This leads to higher temperatures within the combustion chamber,resulting in increases in the end gas temperature of the incomingcharge. Consequently, end gas auto-ignition occurs, which causes engineknock. In addition, the accumulation of deposits within the combustionchamber reduces the volume of the combustion zone, causing a higher thandesign compression ratio in the engine. This, in turn, also results inserious engine knocking. A knocking engine does not effectively utilizethe energy of combustion. Moreover, a prolonged period of engineknocking will cause stress fatigue and wear in vital parts of theengine. The above-described phenomenon is characteristic of gasolinepowered internal combustion engines. It is usually overcome by employinga higher octane gasoline for powering the engine, and hence has becomeknown as the engine octane requirement increase (ORI) phenomenon. Itwould therefore be highly advantageous if engine ORI could besubstantially reduced or eliminated by preventing deposit formation inthe combustion chamber of the engine.

An additional problem common to internal combustion engines relates tothe accumulation of deposits in the carburetor which tend to restrictthe flow of air through the carburetor at idle and at low speed,resulting in an overrich fuel mixture. This condition also promotesincomplete fuel combustion and leads to rough engine idling and enginestalling. Excessive hydrocarbon and carbon monoxide exhaust emissionsare also produced under these conditions. It would therefore bedesirable from the standpoint of engine operability and overall airquality to provide a motor fuel composition which minimizes or overcomesthe above described problems.

Deposit-inhibiting additives for use in motor fuel compositions are wellknown in the art. However, conventional additives may cause hazing ofthe motor fuel. Hazy motor fuels are unacceptable by the public sincethey may indicate a problem with the fuel, such as the presence ofundesired contaminants. It would therefore be desirable to provide ahaze-free motor fuel composition which is deposit-resistant andORI-inhibited.

The instant invention discloses a novel gasoline-soluble polyetherdiamine compound which, when employed in a motor fuel composition,minimizes the tendency of the motor fuel to form deposits. Consequently,engine ORI is substantially reduced by employing the polyether diamineof the instant invention in motor fuel compositions. Motor fuelcompositions of the instant invention are also haze-free, clear, andstable.

2. Disclosure Statement

Co-assigned U.S. patent applications Ser. No. 000,230, filed Jan. 1,1987, discloses a novel gasoline-soluble reaction product and the use ofthe reaction product as an ORI-inhibitor in motor fuel compositions. Thenovel reaction product is obtained by reacting:

(i) about 1 mole of a dibasic acid anhydride:

(ii) 1-2 moles of a polyoxyalkylene diamine, and

(iii) 1-2 moles of a hydrocarbyl polyamine.

Co-assigned U.S. Pat. No. 4,581,040 teaches the use of a reactionproduct as a deposit inhibitor additive in fuel compositions. Thereaction product taught is a condensate product of the processcomprising:

(i) reacting a dibasic acid anhydride with a polyoxyisopropylenediamineof the formula ##STR1## where x is a numeral of about 2-50, therbyforming a maleamic acid; (ii) reacting said maleamic acid with apolyalkylene polyamine, thereby forming a condensate product; and

(iii) recovering said condensate product.

Co-assigned U.S. Pat. No. 4,659,336, filed on Mar. 28, 1986 disclosesthe use of the mixture of: (i) the reaction product of maleic anhydride,a polyether polyamine containing oxyethylene and oxypropylene ethermoieties, and a hydrocarbyl polyamine; and (ii) a polyolefinpolymer/copolymer as an additive in motor fuel compositions to reduceengine ORI.

Co-assigned U.S. Pat. No. 4,659,337, filed on Jan. 23, 1986 disclosesthe use of the reaction product maleic anhydride, a polyether polyaminecontaining oxyethylene and oxypropylene ether moieties, and ahydrocarbyl polyamine in a gasoline motor fuel to reduce engine ORI andprovide carburetor detergency.

U.S. Pat. No. 4,604,103 discloses a motor fuel deposit control additivefor use in internal combustion engines which maintains cleanliness ofthe engine intake system without contributing to combustion is ahydrocarbyl polyoxyalkylene polyamine ethane of molecular weight range300-2500 having the formula: ##STR2## where R is a hydrocarbyl radicalof from 1 to about 30 carbon atoms; R' is selected from methyl andethyl; x is an integer from 5 to 30; and R" and R'" are independentlyselected from hydrogen and (CH2CH2NH )_(y) H' where y is an integer from0-5.

U.S. Pat. No.4,357,148 discloses the use of the combination of anoil-soluble aliphatic polyamine component containing at least oneolefinic polymer chain and having a molecular weight range of600-10,000, and a polymeric component which may be a polymer, copolymer,hydrogenated polymer or copolymer, or mixtures thereof having amolecular weight range of 500-1500 to reduce or inhibit ORI in motorfuels.

U.S. Pat. No. 4,191,537 discloses the use of a hydrocarbylpolyoxyalkylene aminocarbonate, having a molecular weight range of600-10,000 and also having at least one basic nitrogen atom peraminocarbonate molecule, to reduce and control ORI in motor fuels.

Co-assigned U.S. Pat. No. 3,502,451 discloses the use of C₂ -C₆polyolefin polymers or hydrogenated polymers having a molecular weightrange 500-3500 in motor fuels to eliminate or reduce deposition on theintake valves and ports of an internal combustion engine.

U.S. Pat. No. 3,438,757 discloses the use of branched chain aliphatichydrocarbyl amines and polyamines having molecular weights in the range425-10,000 to provide detergency and dispersancy in motor fuels.

Co-assigned Rep. of SOuth Africa Application No. 731911, filed on Mar.19, 1973, discloses a motor fuel composition comprising a polymericcomponent which is a polymer or copolymer of a C2-C6 unsaturatedhydrocarbon having a molecular weight in the range 500-3500, and ahydrocarbyl-substituted amine or polyamine component, said motor fuelcomposition having effectiveness in reducing engine intake valve andport deposits.

Co-assigned U.S. Pat. No. 4,316,991 discloses a modified polyol compoundhaving a molecular weight range of 2000-7000, produced by reacting aninitiator having an active hydrogen functionality of 3-4, one or morealkylene oxides, and an epoxy resin.

U.S. Pat. No. 3,654,370 discloses a method of preparing polyoxyalkylenepolyamines by treating the corresponding polyoxyalkylene polyol withammonia and hydrogen over a catalyst prepared by the reduction of amixture of nickel, copper, and chromium oxides. The polyoxalkylenepolyamines formed are of the formula: ##STR3## wherein R is the nucleusof an oxyalkylation-susceptible polyhydric alcohol containing 2-12carbon atoms and 2-8 hydroxyl groups, Z is an alkyl group containing1-18 carbon atoms, X and Y are hydrogen or Z, n has an average value of0-50 and m is an integer of 2-8 corresponding to the number of hydroxylgroups in the polyhydric alcohol.

U.S. Pat. No. 3,535,307 discloses the preparation of high molecularweight polyether block copolymers the sequential alkoxylation of apolyfunctional initiator with alkylene epoxide components.

Co-assigned U.S. Pat. No. 4,747,851 discloses polyoxyalkylene diaminecompounds and ORI-inhibited motor fuel composition containing same.

SUMMARY OF THE INVENTION

The present invention relates to novel diamine containing blockcopolymers with polyether backbones useful for inhibiting carbonaceousdeposit formation, motor fuel hazing, and as an ORI inhibitor whenemployed as a soluble additive in a motor fuel composition. The novelpolyether diamine compound of the instant invention is obtained by firstpreparing a polyol precursor by reacting a polyethylene glycol withethylene oxide, and butylene oxide, and thereafter catalyticallyaminating the polyol with ammonia and hydrogen over anickel-chromium-copper metal and metal oxide catalyst to produce a novelpolyoxyalkylene diamine of the formula: ##STR4## where b has a valuefrom about 10-80, preferably 20-60, and a+c has a value from about10-50, preferably 20-40.

The instant invention is also directed to a concentrate comprising1.0-75.0 weight percent, preferably 5.0-35.0 weight percent of theprescribed novel polyether diamine dissolved in a hydrocarbon solvent,preferably xylene. In addition, the instant invention is directed to ahaze-free, deposit-resistant and ORI-inhibited motor fuel compositioncomprising 0.0005-1.0 weight percent, preferably 0.001-0.5, mostpreferably 0.01-0.1 weight percent of the prescribed reaction product.An additional polymer/copolymer additive with a molecular weight rangeof 500-3500, preferably 650-2600 may also be employed in admixture withthe motor fuel composition of the instant invention in concentrations of0.001-1.0 weight percent, preferably 0.01-0.5 weight percent.

DETAILED EMBODIMENTS OF THE INVENTION

The novel polyether diamine compound of the instant invention is adiamine of the formula: ##STR5## where b has a value from about 10-80,preferably 20,60 and a+c has a value from about 10-50, preferably 20-40.The novelty of the prescribed polyether diamine compound resides in theunique structure of the compound not heretofore disclosed.

The novel polyether diamine of the instant invention is obtained byfirst preparing a polyol precursor, and thereafter catalyticallyaminating the polyol to produce the polyether diamine. The polyolprecursor is prepared by reacting a polyethylene glycol of anapproximate molecular weight of 100-3000, preferably about 600, with anaqueous alkali metal hydroxide, preferably potassium hydroxide. Thereactor is then supplied with a nitrogen gas purge and heated to about95°-120° C., preferably about 100° C., and dried of water. Ethyleneoxide is then charged in to the reactor and reacted at a temperature of95°-120° C., preferably about 50 psig. Without digestion, butylene oxideis then charged in to the reactor and reacted at a temperature of95°-120° C., preferably 105°-110° C., and a pressure of 10-100 psig,preferably about 50 psig.

After allowing for a digestion period, the alkaline polyol reactionproduct is neutralized with magnesium silicate, which may be added tothe reaction mixture as a solid or as an aqueous solution. A magnesiumsilicate particularly suitable for use in neutralizing the alkalinepolyol is MAGNESOL 30/40, commercially available from Reagent Chemicaland Research Inc. After neutralization, di-t-butyl-p-cresol is added tostabilize the polyol, and the polyol is thereafter stripped and filteredto yield the final polyol precursor compound.

Amination of the above-described polyol precursor is accomplished asfollows. A tubular reactor is filled with a nickel-chromium-copper metaland metal oxide catalyst. ,Such a catalyst is described, for example, inU.S. Pat. No. 3,654,370, incorporated herein by reference. The reactoris heated to a temperature of 190°-220° C., preferable about 200° C.,and a pressure of 500-4000 psig, preferably about 2000 psig. The polyolprecursor is fed into the reactor at a flow rate of about 0.1-1.0,preferably about 0.6 g/cc-cat/hr. Ammonia is fed into the reactor at arate of about 0.2-6.0, preferable about 12 lb/1 b-polyol. Hydrogen isfed into the reactor at a flow rate of about 1-10, preferably about 2SCF/lb-polyol. The effluent is then stripped at about 85°-175° C.,preferably about 100° C., and 0.1-150 mm Hg, preferably abut 10 mm Hgvacuum, to obtain the novel polyether diamine of the instant invention.The best mode of synthesis of the prescribed novel polyether diaminecompound of the instant invention is set forth in Example I, below.

EXAMPLE I Synthesis of Novel Polyether Diamine Reactant

A. Preparation of Polyol Precursor

Ten pounds of a polyethylene glycol of an approximate molecular weightof 600 and 100 g of 45% aqueous KOH is charged into a ten-gallonreactor, which is then purged with prepurified nitrogen. Whilemaintaining a nitrogen purge, the reactor is heated to 100° C., and aninitiator is then dried to a water content of less than 0.1% by vacuumstripping followed by nitrogen stripping. Thereafter, 19 lb of ethyleneoxide is charged and reacted at 105°-110 C. and 50 psig for 1.25 hours.Without digestion, 33 lbs of butylene oxide is then charged and reactedat 110-120° C. and 50 psig over a 3 hour period.

After a 2 hour digestion period, the alkaline polyol is neutralized bystirring for 2 hours with about 360 g of MAGNESOL 30/40, which is addedas an aqueous slurry. To stabilize the material, about 26.4 g ofdi-t-butly p-cresol is added. The neutralized product is then vacuumstripped to about 5 mm Hg pressure, nitrogen stripped, and filtered. Thefinished product will be generally characterized by the followingrepresentative properties:

    ______________________________________                                        Acid no., mg KOH/g  0.01                                                      Hydroxyl no., mg KOH/g                                                                            35                                                        Water, wt %         0.01                                                      pH in 10:6 isopropanol-water                                                                      8.1                                                       Color, Pt-Co        40                                                        Sodium, ppm         0.2                                                       Potassium, ppm      0.2                                                       Peroxide, ppm       1.1                                                       Viscosity, ° F., cc                                                     77                 988                                                       100                 513                                                       ______________________________________                                    

B. Amination Reaction

0.6 lb/hr of the polyol prepared under A,, 1.2 lb/hr of ammonia, and 36liter/hr of hydrogen are fed into a 1250 ml tubular reactor filled witha nickel-chromium-copper metal and metal oxide catalyst which is kept at200° C. and 2000 psig. The reactor effluent is stripped at 100° C. and10 mm Hg vacuum. The resulting polyether polyamine product will begenerally characterized by the following representative properties:

    ______________________________________                                        Total acetylatables, meq/g                                                                        0.615                                                     Total amine, meq/g  0.56                                                      Primary amine, meq/g                                                                              0.54                                                      Water, wt %         0.09                                                      Color, Pt-Co        30                                                        Flash Point, PMCC   440° F.                                            Melting point, ° C.                                                                        27-31                                                     ______________________________________                                    

A critical feature of the novel olyether diamine compound of the instantinvention is the presence of a large number (10-50 preferably 20-40) ofpolyoxybutylene ether moieties. In particular, the presence of a largenumber of polyoxybutylene ether moieties enhances the gasolinesolubility of the compound, thus increasing its efficiency as anadditive in motor fuel compositions. The novel polyether diaminecompound of the invention requires no admixing with a solvent prior tointroduction into a base motor fuel composition.

The motor fuel composition of the instant invention comprises a majoramount of a base motor fuel and 0.0005-1.0 weight percent, preferably0.001-0.5, most preferably 0.01-0.2 weight percent of theabove-described novel polyether diamine. Preferred base motor fuelcompositions for use with the polyether diamine additive are thoseintended for use in spark ignition internal combustion engines. Suchmotor fuel compositions, generally referred to as gasoline base stocks,preferably comprise a mixture of hydrocarbons boiling in the gasolineboiling range, preferably from about 90° F. to about 450° F. This basefuel may consist of straight chain or branched chain paraffins,cycloparaffins, olefins, aromatic hydrocarbons, or mixtures thereof. Thebase fuel can be derived from, among others, straight run naphtha,polymer gasoline, natural gasoline, or from catalytically reformedstock. The composition and octane level of the base fuel are notcritical and any conventional motor fuel base can be employed in thepractice of this invention. In addition, the motor fuel composition maycontain any of the additives generally employed in gasoline. Thus, thefuel composition can contain anti-knock compounds such as tetraethyllead compounds, anti-icing additives, upper cylinder lubricating oils,and the like.

The motor fuel composition of the instant invention may additionallycomprise a polymeric component, present in a concentration ranging fromabout 0.001-1.00 weight percent, preferably 0.01-0.5 weight percent,based on the total weight of the motor fuel composition. The polymericcomponent may be a polyolefin polymer, copolymer, or correspondinghydrogenated polymer or copolymer of a C₂ -C₆ unsaturated hydrocarbon.The polymer component is prepared from monoolefins and diolefins, orcopolymers thereof, having an average molecular weight range from about500-3500, preferably about 650-2600. Mixtures of olefin polymers with anaverage molecular weight within the foregoing range are also effective.In general, the olefin monomers from which the polyolefin polymercomponent is prepared are unsaturated C₂ -C₆ hydrocarbons. Specificolefins which may be employed to prepare the polyolefin polymercomponent include ethylene, propylene, isopropylene, butylene,isobutylene, amylene and hexylene. Propylene, isopropylene, butylene andisobutylene are particularly preferred for use in preparing thepolyolfin component. Other polyolefins which may be employed are thoseprepared by cracking polyolefin polymers or copolymers of high molecularweight to a polymer in the above-noted molecular weight to a polymer inthe above-noted molecular weight range. Derivatives of the notedpolymers obtained by saturating the polymers by hydrogenation are alsoeffective. The word "polymers" is intended to include the polyolefinpolymers and their corresponding hydrogenated derivatives. The averagemolecular weight range of the polymer component is important. Thepolyolefin polymer, copolymer, or corresponding hydrogenated polymer orcopolymer component may have an average molecular weight in the rangefrom about 500-3500, preferably from about 650-2600. The most preferredpolymer components for use in the instant invention are polypropylenewith an average molecular weight in the range of about 750-1000,preferably about 800, and polyisobutylene with an average molecularweight in the range of about 1000-1500, preferably about 1300. Thepolymer component, if employed, enhances the ORI reduction of theinstant invention, and additionally provides enhanced cleanliness at theengine intake valves and ports.

The motor fuel compositions of the instant invention are surprisinglyeffective in minimizing and reducing the ORI of a gasoline internalcombustion engine. This improvement may be demonstrated in engine testswhere the performance characteristics of a base motor fuel compositioncontaining a commercial fuel additive and the improved motor fuelcompositions of the instant invention are compared.

A base motor fuel suitable for the tests (herein designated as Base FuelA) is a premium grade gasoline essentially unleaded (less than 0.05 g oftetraethyl lead per gallon), and comprising a mixture of hydrocarbonsboiling in the gasoline boiling range consisting of about 22% aromatichydrocarbons, 11% olefinic hydrocarbons, boiling in the range from about90° F. to 450° F. In preparing motor fuels for an engine test, asuitable amount of the novel polyether diamine compound of the instantinvention is added directly to Base Fuel A without any additionalsolvents being necessary.

The specific engine test suitable for determining engine ORI is made ona 1.8 liter Chevrolet four cylinder engine. This test correlates wellwith results obtained via road simulation tests. The engine test employsa 1.8 liter Chevrolet in-line four cylinder engine with a cast alloyiron cylinder head having separate intake and exhaust ports for eachcylinder. An electronically controlled fuel injection system maintainsthe required fuel flow to each engine cylinder by monitoring variousengine operating parameters (e.g. manifold absolute pressure, throttlevalve position, coolant temperature, engine r.p.m., and exhaust gasoxygen content) and adjusting the fuel flow accordingly. The fuel systemsupplying fuel to the engine is specifically adapted for thedetermination of engine ORI. At the beginning of the engine ratingprocedure, a fuel with an octane rating high enough to ensure that noaudible engine knock is present is employed. The next lower octane fuelis then switched with the previous fuel, and this procedure continuesuntil a knock becomes audible. The difference between the octane levelat knock and no-knock conditions is the engine ORI Engine ORI isdetermined as a function of hours of engine operation.

Example II, set forth below, is illustrative of the ORI phenomenonexhibited by a conventional motor fuel composition.

EXAMPLE II

The ORI tendencies of Base Fuel A containing 60 PTB of a commercial fueladditive (60 pounds of additive per 1000 barrels of gasoline, equivalentto about 0.02 weight percent of additive based upon the weight of thefuel composition) were measured using the above-described Chevrolet 1.8liter engine. After about 225 hours of engine operation, the motor fuelcomposition of Base Fuel A containing 60 PTB of commercial fuel additiveexhibited an ORI of 8-9 octane numbers.

The addition of an effective amount of the prescribed polyether diamineof the invention in a motor fuel composition will modify or reduce theORI build up in an engine.

For convenience in shipping and handling, it is useful to prepare aconcentrate of the novel polyoxyalkylene diamine compound which may beadded to a base motor fuel to produce the motor fuel composition of theinstant invention. The concentrate may be prepared in a suitable liquidsolvent containing from about 1.0-75.0 weight percent, preferably5.0-35.0 weight percent of the additive component or components: namely,the above-described novel polyoyalkylene diamine compound either aloneor in combination with the above-described additional polymer component.Suitable solvents for use in the concentrate include hydrocarbonsolvents such as toluene and xylene, with xylene being preferred.

It will be evident that the terms and expressions employed herein areused as terms of description and not of limitation. There is nointention, in the use of these descriptive terms and expressions, ofexcluding equivalents of the features described and it is recognizedthat various modifications are possible within the scope of theinvention claimed.

The invention claimed is:
 1. A polyether diamine compound of theformula: ##STR6## where b has a value from about 10-80 and a+c has avalue from about 12 to
 40. 2. A compound as set forth in claim 1,wherein b has a value of about 20-60 and a+c has a value from about 20to
 40. 3. A concentrate composition comprising 1.0-75.0 weight percentof a polyoxyalkylene diamine of the formula: ##STR7## in admixture witha hydrocarbon solvent, where b has a value from about 10 to 80 and a+chas a value from about 12 to
 40. 4. A concentrate composition accordingto claim 3, wherein b has a value from about 20 to 60 and a+c has avalue from about 20 to
 40. 5. A concentrate composition according toclaims 3 or 4, where said polyether diamine is present in aconcentration range of 5.0-35.0 weight percent.
 6. A motor fuelcomposition comprising a mixture of hydrocarbons boiling in the rangefrom about 90° F.-450° F. and from 0.0005-1.0 weight percent of apolyether diamine of the formula: ##STR8## where b has a value fromabout 10-80 and a+c has a value from about 12 to
 40. 7. A motor fuelcomposition according to claim 6, wherein b has a value from about 20 to60 and a+c has a value from about 20 to
 40. 8. A motor fuel compositionaccording to claim 6, comprising from about 0.001-0.5 weight percent ofsaid polyether diamine additive.
 9. A motor fuel composition accordingto claim 7, comprising from about 0.01-0.2 weight percent of saidpolyether diamine additive.
 10. A motor fuel composition according toclaim 6, which additionally comprises from about 0.001-1.0 weightpercent of a polyolefin polymer, copolymer, or the correspondinghydrogenated polymer, or copolymer, or mixtures thereof, of a C2-C6unsaturated hydrocarbon, said polyolefin polymer or copolymer having amolecular weight in the range from about 500-3500.
 11. A motor fuelcomposition according to claim 10, in which said polyolefin polymer orcopolymer component is derived from an unsaturated hydrocarbon selectedfrom the group consisting of ethylene, propylene, isopropylene,butylene, isobutylene, amylene, hexylene, isoprene, and butadiene.
 12. Amotor fuel composition according to claim 11, in which said polyolefinpolymer, copolymer, or corresponding hydrogenated polymer or copolymercomponent has a molecular weight in the range of about 650-2600.
 13. Amotor fuel composition according to claim 12, in which said polyolefinpolymer component is a polypropylene having a molecular weight in therange of about 750-1000.
 14. A motor fuel composition according to claim13, where said polyolefin polymer component is a polypropylene with anaverage molecular weight of about
 800. 15. A motor fuel compositionaccording to claim 12, in which said polyolefin polymer component is apoly-isobutylene having a molecular weight in the range of about1000-1500.